The Grammy-winning singer posted a picture of the two on his Instagram page Saturday morning saying the two got engaged right before the new year.
He said they are "very happy and in love" and that their "cats are chuffed as well."
In 2013, she was enrolled in the master of management studies program at Duke University's Fuqua School of Business. Seaborn was also a field hockey star during her time at Duke.
Sheeran said last fall how Seaborn inspired his song "Perfect," which is Number One on the Billboard Hot 100 charts.
Sheeran and Seaborn were friends when the two attended school in Suffolk, England. They reconnected years later.
The Associated Press contributed to this story.